Strategies of elite Chinese gymnasts in coping with landing impact from backward somersault

Figures

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  Figure 1. Location of retro-reflective markers and EMG sensors on the gymnasts (A–C), 19 segments human model generated by GEBOD in LifeMOD™ (D).

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  Figure 2. The demonstration of backward somersault landing. T0: The pre-activation phase was defined as 100 ms preceding ground contact; T1: initial impact-phase, from the first touchdown to the peak vertical ground reaction force (vGRF); T2: terminal impact-phase, from the peak vGRF to the vGRF equaling to body weight.

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  Figure 3. Average integrated (20 ms bins) angles of lower extremity joints (A–C) and vertical ground reaction force (vGRF) (D) during backward somersault landing (n = 6). The whole landing process was divided into three phases by solid vertical lines. T0: The pre-activation phase was defined as 100 ms preceding ground contact; T1: initial impact-phase, from the first touchdown to the peak vGRF; T2: terminal impact-phase, from the peak vGRF to the vGRF equaling to body weight (Mean: solid vertical line, standard deviation: dotted vertical line).

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  Figure 4. Average integrated (20 ms bins) angular velocities of lower extremity joints during backward somersault landing (A–C) (n = 6). The solid arrow indicates that the acceleration is negatively increasing, and the dotted arrow indicates that the acceleration is negatively decreasing. The whole landing process was divided into three phases by solid vertical lines. T0: The pre-activation phase was defined as 100 ms preceding ground contact; T1: initial impact-phase, from the first touchdown to the peak vertical ground reaction force (vGRF); T2: terminal impact-phase, from the peak vGRF to the vGRF equaling to body weight (Mean: solid vertical line, standard deviation: dotted vertical line).

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  Figure 5. Average integrated (20 ms bins) coactivation of root mean square of normalized EMG (EMGRMS) (n = 6). Positive EMGRMS means antagonist of the joint, and negative EMGRMS means the agonist of the joint. The EMGs were normalized to the peak EMG during the landing phase. RF, rectus femoris; BF, biceps femoris; TA, tibialis anterior; LG, lateral gastrocnemius. The coactivation was defined as the TA to LG EMG for the ankle (A and C), and the BF to RF EMG for the knee (B and D). The whole landing process was divided into three phases by solid vertical lines. T0: The pre-activation phase was defined as 100 ms preceding ground contact; T1: initial impact-phase, from the first touchdown to the peak vertical ground reaction force (vGRF); T2: terminal impact-phase, from the peak vGRF to the vGRF equaling to body weight (Mean: solid vertical line, standard deviation: dotted vertical line).

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  Figure 6. The angles (A and B), angular velocities (C and D) and torques (E and F) of lower extremity joints for one of the gymnasts during backward somersault landing (n = 1). The skeleton models showed four body postures of the landing (100 ms prior touchdown, touchdown, peak vertical ground reaction force (vGRF), and vGRF equal to body weight, respectively). The whole landing process was divided into three phases by solid vertical lines. T0: The pre-activation phase was defined as 100 ms preceding ground contact; T1: initial impact-phase, from the first touchdown to the peak vGRF; T2: terminal impact-phase, from the peak vGRF to the vGRF equaling to body weight.